Compact earth excavators are usually tilted at an angle of a few degrees, meaning that they are a little higher in the front end than in the back end, when in operation. This will have the effect that slewing of the excavator occurs whenever the slewing torque of the excavator exceeds the resisting torque of the slewing gear. Slewing or swinging is the rotational movement of the superstructure (such as a crane) relative to the undercarriage. A slewing gear or swinging gear is the system, which provides the movement.
In order to increase the resisting torque of the slewing gear, gerotor motors have been made with what is called a tight gear set. This means that the internal gear wheel of the gear set of the motor has to be forced around inside the external gear wheel. However, a tight gear set will only apply resistance against rotation in some positions. What is happening, is:
Torque is applied to the slewing gear from load in the bucket.
Pressure inside the motor will try to resist the slewing, but internal leaking of fluid means that only the slewing speed is reduced.
The tight gear set will add additional resistance against slewing when first resistance position is reached, whereby the slewing is stopped.
Internal leaking of fluid will reduce the pressure, whereby only the tight gear set will apply resistance against slewing.
If the tight gear set is not able to resist the slewing, it will move on, until the next resistance position is reached.
A tight gear set can be made with sufficient resistance to resist the slewing. Wear of the gear set will, however, reduce the resistance, and an effective prevention of slewing is only obtained for a short period of the lifetime.
Therefore, a principal object of this invention is to provide a brake appliance for a gerotor motor that will effectively provide an effective braking torque to resist torque of the slewing gear wheel when associated with a gerotor motor driven vehicle susceptible to developing slewing torque.
A further object of this invention is to provide a brake appliance for gerotor motors that has a disc assembly brake comprising interacting discs that are subjected to opposing forces from pressurized fluid in one direction to disengage the discs, and from dynamic forces in the opposite direction to engage the discs.
These and other objects will be apparent to those skilled in the art.
A brake appliance for gerotor motors to provide resistance to slewing torque imposed upon the output shaft of such a motor includes a disc-type brake involving oppositely disposed interacting braking discs that are subjected to opposing forces from pressurized fluid in one direction to disengage the discs, and from dynamic forces in the opposite direction to engage the discs. The spring forces are provided by a series of spring springs mounted on a slidable piston plate to move the discs into braking engagement with each other.